Imaging device and imaging apparatus generating image information for each of plural pixels from received light

ABSTRACT

An imaging apparatus includes an imaging device which includes a plurality of pixels and is operable to generate image information for each pixel from received light. Each of the plurality of pixels includes one of first to fourth color filters. Each of the first to the fourth color filters has different spectral characteristics. The fourth color filter has the highest light transmittance among the color filters. The first to the fourth color filters are arranged in a specific array. The specific array has first to third centroids which make a Bayer array.

BACKGROUND

1. Technical Field

The present disclosure relates to an imaging device including severalkinds of color filters and an imaging apparatus including the imagingdevice.

2. Related Art

JP 2010-136225 A describes an imaging device which includes a pixelarray part in which pixels are arranged in a two-dimensional matrix witha color for a main component of luminance signal checkered on the matrixand a plurality of colors for color information components arrayed onthe remaining portions. JP 2010-136225 A describes the effect that theimaging device converts a signal corresponding to each color of thecolor array on a color filter part, which is output from each pixel ofthe pixel array part, into a signal corresponding to the Bayer array andoutputs the signal.

SUMMARY

In recent years, digital cameras capable of taking not only a stillimage but also a moving image by using the same imaging device have beenmore widely used. In addition, pixels of the imaging device have beenmade finer so that data of finer image information can be recorded.

Since a still image is taken one by one in principle, a time requiredfor various image process is ensured to some extent. Therefore, evenwhen the highly fine imaging device has increased the amount ofinformation to be processed, the image may be processed in a relativelyeasy way.

On the other hand, the digital camera takes tens of images per second inshooting a moving image. For example, the digital camera takes sixtyimages per second. That is, as compared to the case of taking a stillimage, the amount of information needed to be processed in a unit timeis remarkably large in shooting a moving image.

Further, a technique of adding pixels for the fourth color (for example,white) to the pixels of the imaging device (red, green, and blue) isknown. That further increases the amount of information to be outputfrom the imaging device.

As described above, the digital camera takes tens of images per secondin shooting a moving image. For example, the digital camera takes sixtyimages per second to obtain a smooth moving image. That is, as comparedto the case of taking a still image, the amount of information needed tobe processed in a unit time is remarkably large in shooting a movingimage. Therefore, the digital camera having the highly fine imagingdevice needs to be improved in the output from the imaging device sothat taking a smooth moving image as well as a still image by using thesame imaging device is capable.

The present disclosure concerns an imaging device which can shoot astill image and a moving image and can output a signal more efficiently,and an imaging apparatus including the imaging device.

The imaging apparatus according to the present disclosure includes animaging device which includes a plurality of pixels and is operable togenerate image information for each pixel from received light. Each ofthe plurality of pixels includes one of first to fourth color filters.Each of the first to the fourth color filters has different spectralcharacteristics. The fourth color filter has the highest lighttransmittance among the color filters. The first to the fourth colorfilters are arranged in a specific array. The specific array has firstto third centroids which make a Bayer array, the first centroid is acentroid of a plurality of pixels which are used in a first pixeladdition process performed on pixel information generated based onlights transmitted through the first color filters, the second centroidis a centroid of a plurality of pixels which are used in a second pixeladdition process performed on the pixel information generated based onlights transmitted through the second color filters, and the thirdcentroid is a centroid of a plurality of pixels which are used in athird pixel addition process performed on the pixel informationgenerated based on lights transmitted through the third color filters.Pixel information regarding a color corresponding to the first colorfilters is generated by the first pixel addition process, pixelinformation regarding a color corresponding to the second color filtersis generated by the second pixel addition process, and pixel informationregarding a color corresponding to the third color filters is generatedby the third pixel addition process.

The imaging device according to the present disclosure includes aplurality of pixels and is operable to generate image information foreach pixel from a received light. Each of the plurality of pixelsincludes one of first to fourth color filters. Each of the first to thefourth color filters have different spectral characteristics, the fourthcolor filter has the highest light transmittance among the colorfilters. The first to the fourth color filters are arranged in aspecific array. The specific array has first to third centroids whichmake a Bayer array, the first centroid is a centroid of a plurality ofpixels which are used in a first pixel addition process performed onpixel information generated based on light transmitted through the firstcolor filters, the second centroid is a centroid of a plurality ofpixels which are used in a second pixel addition process performed onthe pixel information generated based on light transmitted through thesecond color filters, and the third centroid is a centroid of aplurality of pixels which are used in a third pixel addition processperformed on the pixel information generated based on light transmittedthrough the third color filters. Pixel information regarding a colorcorresponding to the first color filters is generated by the first pixeladdition process, pixel information regarding a color corresponding tothe second color filters is generated by the second pixel additionprocess, and pixel information regarding a color corresponding to thethird color filters is generated by the third pixel addition process.

The present disclosure can provide an imaging device and an imagingapparatus which can output image information more efficiently.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of a video cameraaccording to a first embodiment.

FIG. 2 is a diagram illustrating spectral sensitivity features of fourkinds of color filters (R, G, B, and W).

FIG. 3 is a diagram illustrating the Bayer array that is a general pixelarray.

FIG. 4 is a diagram illustrating a basic array of color filters in aCMOS image sensor according to the first embodiment.

FIG. 5 is a diagram illustrating a pixel array in the CMOS image sensoraccording to the first embodiment.

FIG. 6 is a flowchart describing operations of the video cameraaccording to the first embodiment.

FIG. 7 is a diagram for describing pixel addition in the firstembodiment.

FIG. 8 is a diagram illustrating positions of the respective pixelsresulting from the pixel addition in the first embodiment.

FIG. 9 is a diagram for describing the pixel addition in a secondembodiment.

FIG. 10 is a diagram illustrating positions of the respective pixelsresulting from the pixel addition in the second embodiment.

FIG. 11 is a diagram illustrating a basic array of color filters in athird embodiment.

FIG. 12 is a diagram illustrating a pixel array in a CMOS image sensoraccording to the third embodiment.

FIG. 13 is a diagram for describing the pixel addition in the thirdembodiment.

FIG. 14 is a diagram illustrating positions of the respective pixelsresulting from the pixel addition in the third embodiment.

FIG. 15 is a diagram for describing the pixel addition in a fourthembodiment.

FIG. 16 is a diagram illustrating positions of the respective pixelsresulting from the pixel addition in the fourth embodiment.

FIG. 17 is a diagram illustrating a basic array of color filters in afifth embodiment.

FIG. 18 is a diagram illustrating a pixel array in a CMOS image sensoraccording to the fifth embodiment.

FIG. 19 is a diagram for describing the pixel addition in the fifthembodiment.

FIG. 20 is a diagram illustrating positions of the respective pixelsresulting from the pixel addition in the fifth embodiment.

FIG. 21 is a diagram for describing the pixel addition in a sixthembodiment.

FIG. 22 is a diagram illustrating positions of the respective pixelsresulting from the pixel addition in the sixth embodiment.

FIG. 23 is a diagram for describing the pixel addition in a seventhembodiment.

FIG. 24 is a diagram illustrating positions of the respective pixelsresulting from the pixel addition in the seventh embodiment.

FIG. 25 is a diagram illustrating a basic array of color filters in aneighth embodiment.

FIG. 26 is a diagram illustrating a pixel array in a CMOS image sensoraccording to the eighth embodiment.

FIG. 27 is a diagram for describing the pixel addition in the eighthembodiment.

FIG. 28 is a diagram illustrating positions of the respective pixelsresulting from the pixel addition in the eighth embodiment.

FIG. 29 is a diagram for describing the pixel addition in a ninthembodiment.

FIG. 30 is a diagram illustrating positions of the respective pixelsresulting from the pixel addition in the ninth embodiment.

FIG. 31 is a diagram for describing the pixel addition in a tenthembodiment.

FIG. 32 is a diagram illustrating positions of the respective pixelsresulting from the pixel addition in the tenth embodiment.

FIG. 33 is a diagram illustrating an array of color filters in aneleventh embodiment.

FIG. 34 is a diagram illustrating an array of color filters in a twelfthembodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 1. First Embodiment

The first embodiment will be described below with reference to theattached drawings. A video camera will be taken as an example of theembodiment.

1-1. Overview

The video camera of the present embodiment is capable of taking a stillimage and a moving image by using the same imaging device (a CMOS imagesensor in the present embodiment). Further, color filters of the CMOSimage sensor installed in the video camera according to the presentembodiment are arrayed to be able to output signals corresponding to theBayer array after four kinds of pixels are mixed. That filter arrayenables the video camera to output image information more efficientlyboth in shooting a still image and in shooting a moving image by usingthe same imaging device.

The configuration and the operation of the video camera according to thepresent embodiment will be described below with reference to thedrawings.

1-2. Configuration of Video Camera

The electrical configuration of the video camera according to the firstembodiment will be described with reference to FIG. 1. FIG. 1 is a blockdiagram illustrating a configuration of the video camera.

The video camera 100 includes an optical system 110, a diaphragm 300, ashutter 130, a CMOS image sensor 140, an A/D converter 150, an imageprocessor 160, a buffer 170, a controller 180, a card slot 190 capableof inserting a memory card 200, a lens driver 120, an internal memory240, an operation member 210, and a display monitor 220.

The video camera 100 captures a subject image formed through the opticalsystem 110, which includes one or more lenses, by the CMOS image sensor140. The image data generated by the CMOS image sensor 140 is subject tovarious image processes by the image processor 160 and stored in thememory card 200. The configuration of the video camera 100 will bedescribed in detail below.

The optical system 110 includes a zoom lens and/or a focus lens. Theoptical system 110 can enlarge and reduce the subject image by movingthe zoom lens along an optical axis. The optical system 110 can alsoadjust the focus on the subject by moving the focus lens along theoptical axis.

The lens driver 120 drives the respective lenses included in the opticalsystem 110. The lens driver 120 includes, for example, a zoom motor fordriving the zoom lens and a focus motor for driving the focus lens.

The diaphragm 300 adjusts the size of the aperture to adjust the amountof incoming light onto the CMOS image sensor 140 automatically oraccording to the setup made by a user.

The shutter 130 is means for shutting off the light to reach the CMOSimage sensor 140.

The CMOS image sensor 140 captures the subject image formed through theoptical system 110 to generate image data. The CMOS image sensor 140performs various operations on exposure, transfer, electronic shutter,and/or the like. The CMOS image sensor 140 has pixels with photodiodescorresponding to the respective pixels provided on it. That is, the CMOSimage sensor 140 has many photodiodes in a two-dimensional array on itslight receptor surface.

The CMOS image sensor 140 also has respective color filters arranged ina predetermined array correspondingly to the pixels. Four kinds of colorfilters are used in the present embodiment. One of the four kinds ofcolor filters is arranged with respect to each pixel. Each pixelreceives the light transmitted the corresponding color filter to outputa signal (image information) according to the intensity of the receivedlight. The color filters of the CMOS image sensor 140 will be describedin detail later.

The CMOS image sensor 140 also has an adder 145 therein. The adder 145performs “pixel addition” to output the signal obtained by the addition.Herein, the “pixel addition” refers to generation of a single signal(image information) by adding signals output from plural pixels of theCMOS image sensor 140. Details of the pixel addition will be describedlater.

The A/D converter (ADC) 150 converts analog image data generated by theCMOS image sensor 140 into digital image data.

The image processor 160 performs operations including generation ofimage data to be displayed on the display monitor 220 and generation ofimage data to be stored in the memory card 200, by performing thevarious processes on the image data generated by the CMOS image sensor140. For example, the image processor 160 performs the various processessuch as gamma correction, white balance correction, and blemishcorrection on the image data generated by the CMOS image sensor 140.Also, the image processor 160 compresses the image data generated by theCMOS image sensor 140 in the form compliant with H.264 standard, MPEG2standard, or the like. The image processor 160 can be implemented with aDSP, a microcontroller, or the like.

The controller 180 is a control device for controlling over the wholevideo camera 100. The controller 180 may be implemented with asemiconductor device or the like. The controller 180 may be configuredof hardware alone or may be implemented with a combination of hardwareand software. The controller 180 may be implemented by a microcontrolleror the like.

The buffer 170 functions as a working memory for the image processor 160and the controller 180. The buffer 170 may be implemented with a DRAM, aferroelectric memory, or the like.

The card slot 190 can store the memory card 200. The card slot 190 canalso be connected to the memory card 200 electrically and mechanically.The memory card 200 has a flash memory, a ferroelectric memory, or thelike therein and can store data including an image file generated by theimage processor 160.

The internal memory 240 includes a flash memory, a ferroelectric memory,and/or the like. The internal memory 240 stores programs such as, forexample, a control program for controlling over the whole video camera100.

The operation member 210 includes a user interface for receiving auser's operation. The operation member 210 includes, for example,directional keys and an OK button for receiving a user's operation, anoperation button for switching modes, a button for instructing to shoota still image, a button for instructing to shoot a moving image, and thelike.

The display monitor 220 can display an image (through image) indicatedby the image data generated in the CMOS image sensor 140 and an imageindicated by the image data read out from the memory card 200. Thedisplay monitor 220 can also display various menu screens and the likefor inputting various settings for the video camera 100.

1-3. Color Filter Array on CMOS Image Sensor

The color filters on the CMOS image sensor 140 according to the presentembodiment will be described in detail below. The CMOS image sensor 140has four kinds of color filters such as a red filter, a green filter, ablue filter, and a white filter. Hereinafter, the red filter, the greenfilter, the blue filter, and the white filter will be respectivelyreferred to as “R filter”, “G filter”. “B filter”, and “W filter”.

FIG. 2 is a diagram illustrating spectral sensitivity features of therespective kinds of color filters. As illustrated in FIG. 2, the Rfilter has a feature of transmitting red colored (R) light, the G filterhas a feature of transmitting green colored (G) light, and the B filterhas a feature of transmitting blue colored (B) light. The W filter has afeature of having higher light transmittance than that of the G filterwhich has the highest light transmittance out of the R filer, the Gfilter, and the B filter, and also has a feature of transmitting lightof the all wavelength ranges.

The color filter array on the CMOS image sensor 140 with the abovedescribed four kinds of color filters will be described below.Hereinafter, the color filter array will also be referred to as pixelarray. FIG. 3 is a diagram illustrating a basic array of the Bayer arraywhich is a general pixel array. FIG. 4 is a diagram illustrating a basicarray of pixels in the CMOS image sensor 140 according to the presentembodiment. The “basic array” is the base unit of array in the pixelarray according to the present embodiment.

In the Bayer array, the three kinds of color filters such as the Rfilter, the G filter, and the B filter are arrayed to repeat the basicarray illustrated in FIG. 3. In the Bayer array, the G filters arecheckered with the R filters and the B filters arrayed adjacent to the Gfilters alone.

Unlike the Bayer array, the basic array of pixels in the CMOS imagesensor 140 includes the four kinds of color filters such as the Rfilter, the G filter, the B filter, and the W filter as illustrated inFIG. 4. The basic array of the pixel array in the present embodiment isthe array with four rows and two columns.

In the CMOS image sensor 140 according to the present embodiment, the Gfilters, which have high contribution ratio to the luminance signal, arecheckered as the G filter The arrangement of checkered G filters canensure the same luminance resolution as that of the Bayer arrayillustrated in FIG. 3.

FIG. 5 is a diagram illustrating the pixel array including the basicarrays illustrated in FIG. 4 repeated horizontally and vertically. FIG.5 illustrates the array with four columns and six rows, which is a partof the repeated pixel array. In fact, the pixels are arrangedcontinuously below, above, on the right, and on the left of the matrixillustrated in FIG. 5. For example, the G filter and the W filter arearrayed above the upper left eight filters and above the upper right sixfilters shown in FIG. 5 according to the basic array, though, thesefilters are omitted in the drawing for convenience of explanation.Similarly, the W filter and the G filter are arranged below the lowerleft four filters and below the lower right four filters in FIG. 5according to the basic array, though, these filters are omitted in thedrawing.

1-4. Operation of Video Camera

The operations of the video camera 100 according to the presentembodiment will be described below. The operations of the CMOS imagesensor 140 installed in the video camera 100 will be described below aswell.

FIG. 6 is a flowchart describing the operations of the video camera 100according to the present embodiment. When the power supply of the videocamera 100 is switched ON, the controller 180 supplies power to therespective units of the video camera 100. As a result, the respectivelenses included in the optical system 110, the CMOS image sensor 140,and the like can perform initial setting. When the optical system 110,the CMOS image sensor 140, and the like finish the initial setting, thevideo camera 100 becomes able to shoot a picture.

The video camera 100 has two modes such as the shooting mode and theplayback mode. The operations of the video camera 100 in the playbackmode will be omitted. When the video camera 100 becomes able to shoot apicture with the shooting mode set, the display monitor 220 starts todisplay the through image captured by the CMOS image sensor 140 andprocessed by the image processor 160.

While the display monitor 220 is displaying the through image, thecontroller 180 monitors whether the instruction button of taking a stillimage is pressed and whether the instruction button of taking a movingimage is pressed. According to press of any instruction button, thecontroller 180 starts to shoot in the instructed mode (S100). That is,when the instruction button of taking a still image is pressed, thecontroller 180 sets the operation mode to the still image mode. When theinstruction button of taking a moving image is pressed, the controller180 sets the operation mode to the moving image mode.

The CMOS image sensor 140 of the video camera 100 according to thepresent embodiment switches the output mode for the image data accordingto the set operation mode (still image mode/moving image mode) (S110).

Specifically, when the operation mode is set to the still image mode (Noin step S110), the CMOS image sensor 140 outputs RAW data whichconfigured by the signals output from all the pixels (S150) withoutcausing the adder 145 to perform the pixel addition on the output fromeach pixel. Thereby, when the still image mode is set, the video camera100 can output highly fine image data.

Herein, the video camera 100 according to the present embodiment has twooutput modes in the moving image mode: a pixel addition mode for theadder 145 of the CMOS image sensor 140 to perform the pixel addition onthe output signal from each pixel, and a pixel non-addition mode for theadder 145 not to perform the pixel addition. The user can previouslyselect either of the pixel addition mode and the pixel non-additionmode. In the moving image mode, the adder 145 of the CMOS image sensor140 switches the output mode for the image data according to thepreviously selected output mode (pixel addition mode/pixel non-additionmode) (S120).

Specifically, when the moving image mode is selected as the operationmode (Yes in step S110), the adder 145 determines whether the outputmode is set to the pixel addition mode (S120).

When the pixel non-addition mode is set (No in step S120), the CMOSimage sensor 140 outputs RAW data which configured by the output signalsfrom all the pixels without performing the pixel addition on the outputsignal from each pixel (S150). Hereinafter, the pixels for which the Rfilter, the G filter, the B filter, and the W filter are provided willbe respectively referred to as “pixel R”, “pixel G”, “pixel B”, and“pixel W”.

For example, when it is desired to output highly fine image data evenwith the frame rate lowered to some extent in shooting the moving imageor when the moving image and the still image are obtained at the sametime, it is effective to output RAW data from all the pixels withoutperforming the pixel addition.

On the other hand, when the pixel addition mode is set (Yes in stepS120), the CMOS image sensor 140 selects the ratio in adding the outputsignals from the respective pixels (R, G, B, and W) in the pixeladdition (S130).

Note that the video camera 100 may not be configured to select the ratioin the pixel addition. In that case, a predetermined addition ratio maybe previously set.

The adder 145 of the CMOS image sensor 140 performs the pixel additionprocess on the output signals from the respective pixels (R, G, B, andW) according to the selected addition ratio. Then, the adder 145 outputsthe signal resulting from the pixel addition (S140). Hereinafter, theoutput signals from the pixels R, G, B, and W will be respectivelyreferred to as “signal R”, “signal G”, “signal B”, and “signal W”.

It is effective to perform the pixel addition on the output signals R,G, B, and W from the respective pixels R, G, B, and W in the abovemanner when, for example, it is desired to obtain a smooth image byraising the frame rate in shooting a moving image or it is desired toimprove the S/N under low illumination intensity.

1-5. Pixel Addition Operation

The pixel addition operation performed by the CMOS image sensor 140 willbe described in detail below.

FIG. 7 is a diagram for describing the pixel addition operation in thepresent embodiment. Note that, in the pixel array illustrated in FIG. 7,the pixel G horizontally adjacent to the pixel R will be referred to as“pixel Gr”, and the pixel G horizontally adjacent to the pixel B will bereferred to as “pixel Gb”. The pixel addition operation is performed inunit of the pixel array with six rows and four columns illustrated inFIG. 7.

The CMOS image sensor 140 performs the operation by using the expression1 below on the output signals (R, Gr, Gb, B, and W) from the respectivepixels (R, Gr, Gb, B, and W) to generate the added signals (R′, Gr′,Gb′, 13′, and W′). For example, The CMOS image sensor 140 adds aplurality of signals Rs (R1 to R4) output from a plurality of pixels Rs(R1 to R4) to generate a signal R′.R′=(R1+R2+R3+R4)/4B′=(B1+B2+B3+B4)/4Gr′=(Gr1+Gr2+Gr3+Gr4)/4Gb′=(Gb1+Gb2+Gb3+Gb4)/4W′=(W1+W2+W3+W4)/4  (Expression 1)

FIG. 8 is a diagram illustrating positions of the respective pixels (R′,Gr′, Gb′, B′, and W′) resulting from the pixel addition process based onthe expression 1. The positions R′, Gr′, Gb′, B′ and W′ indicate thecentroids of the plurality of pixels R, Gr, Gb, B, and W, respectively.For example, the position R′ in FIG. 8 indicates the centroid of theplurality of pixels Rs (R1 to R4). That is the case for the otherpositions Gr′, Gb′, B′, and W′.

The adder 145 performs the pixel addition on the each of signals (R, Gr,Gb, B, and W) to output the respective signals (R′, Gr′, Gb′, B′, andW′) resulting from the pixel addition to the ADC 150. In this time, theeach of signals R′, Gr′, Gb′, B′, and W′ is output deemed a signalgenerated at the respective centroids of a plurality of pixels used forthe pixel addition. For example, the signal R′ is output deemed a signalgenerated at the centroid of a plurality of pixels Rs (R1 to R4).

As illustrated in FIG. 8, the array of the centroids of the plurality ofpixels (R, Gr, Gb, and B) are the same as the Bayer array (FIG. 3),respectively. That is, the adder 145 outputs the signals (R′, Gr′, Gb′,and B′) resulting from the pixel addition in the Bayer array pattern.

That is, in the present embodiment, the CMOS image sensor 140 has thecolor filters (R, G, B, and W) arranged to output the result of thepixel addition process in the Bayer array pattern.

Since the signals (R′, Gr′, Gb′, and B′) are output in the Bayer arraypattern as described above, the present embodiment is advantageous inthat conventional processing devices supporting the Bayer array patternare available as processing devices in the latter stage.

The adder 145 also adds signals Ws output from a plurality of pixels Ws(W1 to W4) to output the signals W's. In this time, the signal W′ isoutput deemed a signal generated at the centroid (the position W′ inFIG. 8) of a plurality of pixels Ws (W1 to W4). As illustrated in FIG.8, the centroid W′ of the plurality of pixels Ws (W1 to W4) matches thecentroid of the positions R′, Gr′, Gb′, and B′. That is, the outputposition W′ for the signal W′ is in the center of the Bayer array, thusthe probability of errors caused by the deviation of the centroid suchas a false color is low even during signal process performed with thesignals R′, Gr′, Gb′, B′, and W′.

1-6. Operation of Image Processor

1-6-1. Signal Processing in Pixel Addition Mode

As described with reference to FIG. 6, in the pixel addition modeselected, the CMOS image sensor 140 outputs the signals R′, Gr′, Gb′,B′, and W′ which are generated by the pixel addition.

The signal processing performed by the image processor 160 when the CMOSimage sensor 140 outputs the signals R′, Gr′, Gb′, B′, and W′ which aregenerated by the pixel addition will be described below.

The image processor 160 generates the luminance signal based on thesignals R′, Gr′, Gb′, B′, and W′ output from the CMOS image sensor 140.

Specifically, the image processor 160 generates the low frequencycomponent YL of the luminance signal from R′L, Gr′L, Gb′L, and B′L whichare the low frequency components of the signals R′, Gr′, Gb′, and B′respectively by using the expression 2 below. The respective constantsin the expression 2 are the coefficients defined in the standardspecification of BTA S-001C.YL=0.213*R′L+0.715*(Gr′L+Gb′L)/2+0.072*B′L  (Expression 2)

Note that the low frequency component YL may be generated based on theexpression 3 below. Herein, the coefficients for the low frequencycomponents R′L, Gr′L, Gb′L, and B′L in the expression 3 are validcoefficients for suppressing the moire which might occur when anachromatic subject is captured.YL=0.25*R′L+0.5*(Gr′L+Gb′L)/2+0.25*B′L  (Expression 3)

Also, the image processor 160 finds the high frequency component YH ofthe luminance signal from the high frequency components Gr′H, Gb′H whichare the high frequency components of the signal Gr′, the signal Gb′respectively by using the expression 4 below.YH=(Gr′H+Gb′H)/2  (Expression 4)

Then, the image processor 160 generates the luminance signal Y byperforming the operation with the expression 5 below.Y=YH+YL+m*W′L,0≦m  (Expression 5)

Specifically, the image processor 160 composes the luminance signal Y byadding the low frequency component W′L of the signal W′ multiplied bythe coefficient m to the found low frequency component YL plus the foundhigh frequency component YH. The coefficient m may be set by thecontroller 180 according to the level of the illumination intensity orthe aperture value of the lens, for example.

Note that the signal W has all the components R, G, and B, thecomponents R and B in the signal W′ (R″ and B″) may be generated by theoperation with the expression 6 below. That is, the components R and Bin the signal W′ (R″ and B″) can be calculated by subtracting the signalR′, the signal B′, the signal Gr′, and the signal Gb′ from the signal W′which are generated by the pixel addition.R″L=W′L−(Gr′L+Gb′L)/2−B′LB″L=W′L−(Gr′L+Gb′L)/2−R′L  (Expression 6)

The image processor 160 may use, as chrominance signals, the foundsignals R″ and B″ added with the signals R′ and B′.

1-6-2. Signal Processing in Pixel Non-Addition Mode

The signal processing in the image processor 160 in the pixelnon-addition mode selected will be described with reference to the pixelarray illustrated in FIG. 5. As described above, FIG. 5 is a diagramillustrating the array of pixels in the CMOS image sensor 140 accordingto the present embodiment.

As illustrated in FIG. 5, since the pixels Gs are checkered as in theBayer array (FIG. 3), high resolution can be expected for the luminancesignal based on the high frequency component GH of the output signal Gfrom the pixel G.

Furthermore, as in the case of the pixel addition, addition of thesignal W to the low frequency component YL of the luminance signal canimprove the sensitivity and the S/N.

Note that the low frequency component WL of the signal W may bemultiplied by the coefficient m and added to the YL component. At thistime, the coefficient m is adjusted by the controller 180 according tothe image sensing conditions.

The expression 7 below corresponds to the above described operation. Theluminance signal Y is composed by adding the high frequency component YHof the luminance signal Y to the low frequency component YL of theluminance signal Y.YL=0.213*RL+0.715*GL+0.072*BL+m*WLYH=GHY=YH+YLm≧0  (Expression 7)1-7. Conclusion of Present Embodiment

The video camera 100 according to the present embodiment includes a CMOSimage sensor 140 which includes a plurality of pixels and is operable togenerate image information for each pixel from received light. Each ofthe plurality of pixels includes one of R filter, B filter, G filter,and W filter. Each of the R filter, B filter, G filter, and W filter hasdifferent spectral characteristics. The W filter has the highest lighttransmittance among the color filters. The R filter, B filter, G filter,and W filter are arranged in a specific array. The specific array hasfirst to third centroids R′, B′, and G′ which make a Bayer array, thefirst centroid R′ is a centroid of a plurality of pixels Rs which areused in a first pixel addition process performed on pixel informationgenerated based on lights transmitted through the R filters, the secondcentroid B′ is a centroid of a plurality of pixels Bs which are used ina second pixel addition process performed on the pixel informationgenerated based on lights transmitted through the B filters, and thethird centroid G′ is a centroid of a plurality of pixels Gs which areused in a third pixel addition process performed on the pixelinformation generated based on lights transmitted through the G filters.Pixel information regarding a color corresponding to the R filter isgenerated by the first pixel addition process, pixel informationregarding a color corresponding to the B filter is generated by thesecond pixel addition process, and pixel information regarding a colorcorresponding to the G filter is generated by the third pixel additionprocess.

The video camera 100 with the above described configuration adds up therespective signals Rs, Bs, and Gs output from the plurality of pixelsRs, Bs, and Gs to generate a single corresponding signal R′, a singlecorresponding signal B′, and a single corresponding signal G′. Then, thevideo camera 100 outputs the generated signals R′, B′, and G′ in theBayer array. As a result, the video camera 100 can output the signals(image information) more efficiently.

2. Second Embodiment

The second embodiment will be described below.

The configuration and the operation of the video camera 100 according tothe present embodiment are basically the same as those of the videocamera 100 of the first embodiment. However, the method of adding pixelsaccording to the present embodiment differs from that of the firstembodiment.

FIG. 9 is a diagram for describing the pixel addition in the presentembodiment. The filter array according to the present embodiment is thesame as that of the first embodiment.

In the first embodiment (FIG. 7), four pixels are added up for each ofthe pixels Grs and Gbs. Unlike that, in the present embodiment, sixpixels are added up for each of the pixels Grs and Gbs. As for thepixels of the other colors (R, B, and W), four pixels are added up as inthe first embodiment.

Specifically, the adder 145 of the CMOS image sensor 140 performs theoperation with the expression 8 below on the output signals from therespective pixels.R′=(R1+R2+R3+R4)/4B′=(B1+B2+B3+B4)/4Gr′=(Gr1+Gr2+Gr3+Gr4+Gr5+Gr6)/6Gb′=(Gb1+Gb2+Gb3+Gb4+Gb5+Gb6)/6W′=(W1+W2+W3+W4)/4  (Expression 8)

FIG. 10 is a diagram illustrating positions of the respective pixels R′,Gr′, Gb′, B′, and W′ resulting from the pixel addition process using theexpression 8. For example, the position Gr′ indicates the centroid ofthe plurality of pixels Grs (Gr1 to Gr6). The adder 145 generates thesignal Gr′ by adding up a plurality of signals Grs (Gr1 to Gr6) andoutputs the signal Gr′ deemed a signal generated at the position Gr′.That is the case for the signals of the other colors R, Gb, B, and W.

Also when the operation is performed using the expression 8, the arrayof the positions of the signals R′, Gr′, Gb′, and B′ resulting from thepixel addition process is the same as the Bayer array as illustrated inFIG. 10. In the present embodiment, the CMOS image sensor 140 has thecolor filters R, G, B, and W arranged to output the result of the pixeladdition process in the Bayer array pattern.

Thereby, the adder 145 can output the signal (image information) moreefficiently as in the first embodiment.

Further, as illustrated in FIG. 10, the adder 145 generates and outputsthe signal W′ resulting from the pixel addition so that the signal W′ isplaced at the center of the Bayer array (R′, Gr′, Gb′, and B). Thatmakes the probability of errors caused by the deviation of the centroidsuch as a false color low even during signal processing performed withthe signals R′, Gr′, Gb′, B′, and W′ as in the first embodiment.

Further, as the number of pixels to be added up increases, the effect ofnoise reduction rises.

3. Third Embodiment

The third embodiment will be described below with reference to FIG. 11to FIG. 14.

The basic array of the present embodiment differs from that of the firstembodiment (FIG. 4). Accordingly, the positions of the pixels to besubject to the pixel addition differ from those of the first embodiment.The configuration and the operation of the video camera 100 except forthe above described points are the same as those of the firstembodiment.

FIG. 11 is a diagram illustrating a basic array of pixels in the presentembodiment.

As illustrated in FIG. 11, the basic array of color filters in thepresent embodiment is the array with six rows and two columns. Also inthe basic array according to the present embodiment, four kinds of colorfilters (R, G, B, and W) are arrayed and the G filters are checkered asin the basic array of the first embodiment (FIG. 4).

FIG. 12 is a diagram illustrating the pixel array including the basicarray according to the present embodiment illustrated in FIG. 11repeated horizontally and vertically. On the practical CMOS image sensor140, the pixel G and the pixel W are arrayed above the upper left twelvefilters and above the upper right twelve filters in FIG. 12 according tothe basic array, though, the array with ten rows and four columns, whichis a part of the arrayed pixels, is illustrated in FIG. 12 forconvenience of explanation. Similarly, the pixel W and G are arrayedbelow the lower left four filters and below the lower right four filtersin FIG. 12 according to the basic array, though, these pixels areomitted in the drawing.

FIG. 13 is a diagram for describing the pixel addition in the presentembodiment. In FIG. 13, the pixel G adjacent to the pixel R isrepresented by “pixel Gr”, and the pixel G adjacent to the pixel B isrepresented by “pixel Gb”. Further, as for the pixel W, the four pixelsWs to be added up are represented by the pixels W1 to W4.

The adder 145 of the CMOS image sensor 140 performs the operation withthe expression 1, which has been described in the first embodiment, onthe output from the respective pixels of the above described array.

FIG. 14 is a diagram illustrating positions of the respective pixels R′,Gr′, Gb′, B′, and W′ resulting from the pixel addition according to thepresent embodiment. For example, the position R′ indicates the centroidof the plurality of pixels Rs (only the pixels represented by Rs withindices). That is the case for the pixels of the other colors Gr, Gb, B,and W. As illustrated in FIG. 14, in the present embodiment, the pixelsW1 to W4, which are in the neighbor to the centroid W′ of the pixels Ws,are subject to the pixel addition on the pixels Ws.

As illustrated in FIG. 14, the array of the centroids R′, Gr′, Gb′, andB′ of the plurality of pixels Rs, Grs, Gbs, and Bs, which are subject tothe pixel addition process, are the same as the Bayer array (FIG. 3). Inthe present embodiment, the CMOS image sensor 140 has the color filters(R, G, B, and W) arranged to output the result of the pixel additionprocess in the Bayer array pattern.

Further, as illustrated in FIG. 14, the signal W′ resulting from thepixel addition is output deemed a signal generated at the centroid W′ ofa plurality of pixels Ws. Since the position W° is placed in the centerof the Bayer array (R′, Gr′, Gb′, and B′), the probability of errorscaused by the deviation of the centroid such as a false color is loweven during signal processing performed with the signals R′, Gr′, Gb′,B′, and W′ as in the first embodiment.

4. Fourth Embodiment

The fourth embodiment will be described with reference to FIG. 15 toFIG. 16. Although the pixel array in the present embodiment is the sameas that of the third embodiment, the number of the pixels to be subjectto the pixel addition differs from that of the third embodiment. Theconfiguration and the operation of the video camera 100 except for theabove described point are the same as those of the third embodiment.

In the third embodiment (FIG. 13), four pixels are added up for each ofthe pixels Grs and Gbs. However, the numbers of the respective pixelsGrs and Gbs to be added up may be other than four as in the secondembodiment (FIG. 9). The adder 145 according to the present embodimentadds up eight pixels for each of the pixels Grs and Gbs.

FIG. 15 is a diagram for describing the pixel addition in the presentembodiment. The adder 145 according to the present embodiment generatesa single signal Gr′ by adding up output signals Gr1 to Gr8 from aplurality of pixels Gr1 to Gr8, and generates a single signal Gb′ byadding up output signals Gb1 to Gb8 from a plurality of pixels Gb1 toGb8. The operations for the pixels of the other colors (R, B, and W) arethe same as those in the third embodiment.

Specifically, the adder 145 performs the operation with the expression 9below.R′=(R1+R2+R3+R4)/4B′=(B1+B2+B3+B4)/4Gr′=(Gr1+Gr2+Gr3+Gr4+Gr5+Gr6+Gr7+Gr8)/8Gb′=(Gb1+Gb2+Gb3+Gb4+Gb5+Gb6+Gb7+Gb8)/8W′=(W1+W2+W3+W4)/4  (Expression 9)

FIG. 16 is a diagram illustrating the centroids of the respective pixelsin the present embodiment. As illustrated in FIG. 16, the centroids Gr′and Gb′ of the plurality of pixels Grs (Gr1 to Gr8) and Gbs (Gb1 toGb8), which are subject to the pixel addition, are the same as thecentroids Gr′ and Gb′ (FIG. 14) of the plurality of pixels Grs (Gr1 toGr4) and Gbs (Gb1 to Gb4) in the third embodiment.

The adder 145 according to the present embodiment outputs the signalsGr′ and Gb′ resulting from the pixel addition deemed signals generatedat the centroids Gr′ and Gb′ of the plurality of pixels Grs and Gbs,respectively.

The pixel addition performed in the above described manner can alsoprovide the same effect as that of the first embodiment.

5. Fifth Embodiment

The fifth embodiment will be described below with reference to FIG. 17to FIG. 20. The basic array of the pixels according to the presentembodiment differs from that of the first embodiment and that of thethird embodiment. The configuration and the operation of the videocamera 100 except for the above described point are the same as those ofthe first embodiment.

FIG. 17 is a diagram illustrating a basic array of the pixels in thepresent embodiment. The basic array according to the present embodimentis the array with four rows and four columns. The basic array accordingto the present embodiment includes four kinds of pixels R, G, B, and Wwith the pixels Gs checkered as in the above described basic arrays ofthe first embodiment and the third embodiment.

FIG. 18 is a diagram illustrating the pixel array on the CMOS imagesensor 140. As illustrated in FIG. 18, the basic array according to thepresent embodiment is horizontally and vertically repeated in the CMOSimage sensor 140. FIG. 18 illustrates the array with six rows and sixcolumns, which is a part of the pixels arrayed in the CMOS image sensor140, for convenience of explanation.

FIG. 19 is a diagram for describing the pixel addition in the presentembodiment. In FIG. 19, the pixel G adjacent to the pixel R isrepresented by “pixel Gr”, and the pixel G adjacent to the pixel B isrepresented by “pixel Gb” as in the first embodiment (FIG. 7) and thethird embodiment (FIG. 13). As for the pixel W, the four pixels Ws to besubject to the pixel addition are represented by the pixels W1 to W4.

The adder 145 of the CMOS image sensor 140 performs the operation withthe expression 1, which has been described in the first embodiment, onthe output from the respective pixels.

FIG. 20 is a diagram illustrating positions of the respective pixels(R′, Gr′, Gb′, B′, and W′) resulting from the pixel addition. Forexample, the position R′ indicates the centroid of the plurality ofpixels Rs (R1 to R4). The signal R′ is output deemed a signal generatedat the position R′. That is the case for the other positions (Gr′, Gb′,B′, and W′).

As illustrated in FIG. 20, the array of the output positions R′, Gr′,Gb′, and B′ for the signals R′, Gr′, Gb′, and B′ resulting from thepixel addition process is the same as the Bayer array (FIG. 3). In thepresent embodiment, the CMOS image sensor 140 has the color filters (R,G, B, and W) arranged to output the result of the pixel addition processin the Bayer array pattern. Further, the position W′ at which the signalW′ is output is in the center of the Bayer array as illustrated in FIG.20, thus the probability of errors caused by the deviation of thecentroid such as a false color is low even during signal processingperformed with the signals R′, Gr′, Gb′, B′, and W′ as in the firstembodiment.

6. Sixth Embodiment

The sixth embodiment will be described below with reference to FIG. 21to FIG. 22. The basic array of the present embodiment is the same asthat of the fifth embodiment. However, the number of the pixels to besubject to the pixel addition in the present embodiment differs fromthat of the fifth embodiment.

The increased number of the pixels to be added up enables furtherimprovement of the S/N. Therefore, the pixel to be added up may beincreased as in the examples illustrated in the second embodiment (FIG.9) and the fourth embodiment (FIG. 15).

FIG. 21 is a diagram for describing the pixel addition in the presentembodiment. The adder 145 according to the present embodiment adds upthe pixels which are more than the pixels for the pixel addition in thefifth embodiment, and adds the pixels R (R3), B (B3), Gr (Gr3), and Gb(Gb3) at the centroids as the objects of the pixel addition. As aresult, the adder 145 calculates the average of five pixels as to thepixels R, B, Gr, and Gb, and calculates the average of eight pixels asto the pixel W.

Specifically, the adder 145 of the CMOS image sensor 140 performs theoperation with the expression 10 below on the output from the respectivepixels.R′=(R1+R2+R3+R4+R5)/5B′=(B1+B2+B3+B4+B5)/5Gr′=(Gr1+Gr2+Gr3+Gr4+Gr5)/5Gb′=(Gb1+Gb2+Gb3+Gb4+Gb5)/5W′=(W1+W2+W3+W4+W5+W6+W7+W8)/8  (Expression 10)

FIG. 22 is a diagram illustrating positions of the respective pixels(R′, Gb′, Gr′, B′, and W′) resulting from the pixel addition in thepresent embodiment. For example, the position R′ indicates the centroidof the plurality of pixels Rs as in FIG. 20. The signal R′ is outputdeemed a signal generated at the position R′. That is the case for theother positions Gb′, Gr′, B′, and W′. As illustrated in FIG. 22, thecentroids R′, Gb′, Gr′, B′, and W′ of the respective pixels of thepresent embodiment are the same as those of the fifth embodiment (FIG.20).

The pixel addition performed in the present embodiment can also providethe same effect as that of the first embodiment.

7. Seventh Embodiment

The seventh embodiment will be described below with reference to FIG. 23to FIG. 24. Unlike the adders 145 according to the above describedembodiments which calculate the arithmetic average of the output signalsfrom the plurality of pixels, the adder 145 according to the presentembodiment calculates the weighted average of the output signals.

FIG. 23 is a diagram for describing the pixel addition in the presentembodiment. The pixel array of the present embodiment is the same asthat of the sixth embodiment (FIG. 21). However, the pixels to besubject to the pixel addition in the present embodiment differs fromthose of the sixth embodiment. In the pixel addition of the presentembodiment, a plurality of pixels Grs and Gbs placed to form a diamondshape are targeted.

FIG. 24 is a diagram illustrating positions of the respective pixels(R′, Gb′, Gr′, B′, and W′) resulting from the pixel addition in thepresent embodiment. For example, the position R′ indicates the centroidof the plurality of pixels Rs as in FIG. 22. The respective centroidsR′, B′, Gr′, Gb′, and W′ in the present embodiment are the same as thoseof the sixth embodiment.

The adder 145 performs the operation with the expression 11 below.R′=(R1+R2+R4+R5)*(1−k)+R3*kB′=(B1+B2+B4+B5)*(1−k)+B3*kGr′=(Gr1+Gr2+Gr4+Gr5)*(1−k)+Gr3*kGb′=(Gb1+Gb2+Gb4+Gb5)*(1−k)+Gb3*kW′=(W1+W8)/2*q+(W2+W7)/2*r+(W3+W6)/2*s+(W4+W5)/2*t  (Expression 11)

In the operation based on the expression 11, the output signal R3 fromthe pixel R3 on the centroid R′, for example, is added after multipliedby the coefficient k which is bigger than the coefficient multiplied bythe other pixels Rs (R1, R2, R4, and R5). That is the case for thesignals of the other colors B3, Gr3, and Gb3. As a result, thecontribution by the signals from the pixels on the centroid to theresult of the pixel addition can be increased.

Note that the coefficients k, q, r, s, and t in the Expression 11 aredecided to meet the conditions indicated by the expression 12 below.0≦k≦1,0≦(q+r+s+t)≦1  (Expression 12)

Note that, although the weighted mean is calculated based on theexpression 11 in the present embodiment, the arithmetic mean may becalculated based on the expression 10.

8. Eighth Embodiment

The eighth embodiment will be described below with reference to FIG. 25to FIG. 28. In the above described first to seventh embodiments, theCMOS image sensor 140 has the pixels Gs checkered on the pixel array.Unlike that, the present embodiment does not have the pixels Gscheckered. However, the present embodiment also has the respectivepixels arrayed to output the result of the pixel addition in the Bayerarray as in the above described first to seventh embodiments.

FIG. 25 is a diagram illustrating a basic array in the presentembodiment. The CMOS image sensor 140 according to the presentembodiment does not have the pixels Gs checkered, though, the CMOS imagesensor 140 outputs the image signals so that the result of the pixeladdition on the signals R, G, B, and W is arranged in the Bayer array.The basic array of the present embodiment is in four rows and fourcolumns and includes four kinds of pixels R, G, B, and W as in the abovedescribed first to seventh embodiments.

FIG. 26 is a diagram illustrating the pixel array including the repeatedbasic arrays of the present embodiment (FIG. 25). FIG. 26 illustratesthe pixel array with six rows and four columns, which is a part of thepixel array of the present embodiment, for convenience of explanation.

FIG. 27 is a diagram for describing the pixel addition in the presentembodiment. The adder 145 according to the present embodiment adds sixpixels with respect to the pixels R and B, and adds four pixels withrespect to the pixels Gr, Gb, and W.

FIG. 28 is a diagram illustrating positions of the respective pixels R′,Gb′, Gr′, B′, and W′ resulting from the pixel addition in the presentembodiment. For example, the position R′ indicates the centroid of theplurality of pixels Rs as in FIG. 22. The adder 145 outputs the signalsR′, Gb′, Gr′, B′, and W′ resulting from the pixel addition deemedsignals generated at the positions R′, Gb′, Gr′, B′, and W′,respectively.

The pixel addition according to the present embodiment can output theimage signals so that the output signals Gs are checkered even thoughthe CMOS image sensor 140 does not have the pixel array with the pixelsGs checkered.

9. Ninth Embodiment

The ninth embodiment will be described below with reference to FIG. 29to FIG. 30. In the above described first to eighth embodiments, thepixels are arrayed horizontally and vertically in order (square array).Unlike them, the pixels of the present embodiment are diagonally arrayed(diagonal array).

Since the diagonal array of the pixel array makes the distance betweenthe pixels as long as 1/√2 of the square array, the embodiment isadvantageous with respect to the resolution in horizontal and verticaldirections.

FIG. 29 is a diagram illustrating the pixel array in the presentembodiment. The pixel array in the present embodiment is the pixel arrayin the first embodiment rotated by 45 degrees. The present embodiment isthe same as the first embodiment except for that point.

The adder 145 performs the pixel addition on the output from the pixelsarrayed as illustrated in FIG. 29. The operation performed at this timemay be the same as that performed in the first embodiment (theexpression 1). For example, the adder 145 adds up the signals Rs togenerate the signal R′. That is the case for the signals of the othercolors Gb, Gr, B, and W.

FIG. 30 is a diagram illustrating positions of the respective pixels R′,Gb′, Gr′, B′, and W′ resulting from the pixel addition in the presentembodiment. For example, the position R′ indicates the centroid of theplurality of pixels Rs. That is the case for the other positions Gb′,Gr′, B′, and W′.

The adder 145 outputs the signal R′ generated by the pixel additiondeemed a signal generated at the position R′. That is the case for thesignals of the other colors Gb′, Gr′ B′, and W′.

As described above, according to the present embodiment, the signals R′,G′, and B′ can be output in the Bayer array pattern and the signal W′can be output to the center position of the Bayer array, even though thepixel array is the diagonal array. As a result, the present embodimentcan reduce a load of image process as the above described embodimentscan.

10. Tenth Embodiment

The tenth embodiment will be described below with reference to FIG. 31to FIG. 32.

FIG. 31 is a diagram for describing the pixel addition in the presentembodiment. The pixel array of the present embodiment is the same asthat of the ninth embodiment (FIG. 29). In the ninth embodiment, fourpixels are added up for each of the pixels Gbs and Grs. Unlike that, inthe present embodiment, six pixels are added up for each of the pixelsGbs and Grs.

The adder 145 of the CMOS image sensor 140 performs the same operationas that performed in the pixel addition of the second embodiment (theexpression 8) to generate the signals R′, Gb′, Gr′, B′, and W′.

FIG. 32 is a diagram illustrating positions of the respective pixels(R′, Gb′, Gr′, B′, and W′) resulting from the pixel addition in thepresent embodiment. The positions R′, Gb′, Gr′, B′, and W′ indicate thecentroids of the plurality of pixels R, Gb, Gr, B, and W, respectively.The adder 145 outputs the generated signals R′, Gb′, Gr′, B′, and W′deemed signals generated at the positions R′, Gb′, Gr′, B′, and W′,respectively.

The present embodiment can also provide the same effect as that of theabove described embodiments.

11. Eleventh Embodiment

The eleventh embodiment will be described below with reference to FIG.33. In the first to tenth embodiments, the W filter is used in the arrayof the color filters of the CMOS image sensor 140, but in the presentembodiment, a yellow filter (hereinafter, referred to as “Ye filter”) isused instead of the W filter. Herein, The Ye filter according to thepresent embodiment has higher light transmittance than that of the Gfilter of the CMOS image sensor 140.

FIG. 33 is a diagram illustrating the pixel array in the presentembodiment. The present embodiment is the same as the first embodiment(FIG. 5) except that the W filter is substituted for the Ye filter. Onthe output signals from the respective pixels illustrated in FIG. 33,the adder 145 according to the present embodiment performs the sameoperation as that performed in the pixel addition in the firstembodiment (the expression 1) to output the signals resulting from theoperation to the centroids of the respective pixels.

The Ye filter is used in the present embodiment as a color filter whichhas higher light transmittance than that of the G filter. However,filters other than the Ye filter may be used as far as the filters havehigher light transmittance than that of the G filter.

12. Twelfth Embodiment

The twelfth embodiment will be described below with reference to FIG.34.

FIG. 34 is a diagram illustrating the pixel array in the presentembodiment. In the present embodiment, a Ye filter, for example, issubstituted for the R filter, and a cyan colored filter (hereinafter,referred to as “Cy filter”) is substituted for the B filter.

On the signals obtained from the respective pixels illustrated in FIG.34, the adder 145 according to the present embodiment performs the pixeladdition so that the signals (image information) output to the ADC 150are in the Bayer array pattern as in the first to eleventh embodiments.

Note that the Ye filter and the Cy filter are used in the presentembodiment, though, color filters other than the Ye filter and the Cyfilter may be used. That is, the color filters may be arrayed so thatthe result of the pixel addition makes the output in the Bayer array.

13. Other Embodiments

The embodiments have been described above. However, the idea of theabove described embodiments is not limited to the above describedembodiments. Other embodiments to which the idea of the above describedembodiments can be applied will be described below together.

Although the CMOS image sensor 140 is exemplified as an imaging devicein the above described embodiments, the imaging device is not limited tothat. For example, the imaging device may be implemented with a CCDimage sensor or an NMOS image sensor.

In the above described embodiments, the pixel addition is not performedin shooting a still image. However, the pixel addition may also beperformed in shooting a still image. For example, the pixel addition maybe performed in continuous shooting.

Further, both the image processor 160 and the controller 180 may beimplemented with a single semiconductor chip or may be implemented withseparate semiconductor chips.

Although the CMOS image sensor 140 has the adder 145 therein thatperforms the pixel addition to output the added up pixels in the abovedescribed embodiments, the idea of the above described embodiments isnot limited to that. That is, an arithmetic processor (for example, theimage processor 160) in the stage later than the CMOS image sensor 140may be adapted to perform the pixel addition. Also thereby, a signal(image information) can be output more efficiently.

As described above, according to the above described embodiments, thearray of the signals generated by the CMOS image sensor 140 can beconverted into the array of the Bayer pattern of high processefficiency, by the pixel addition. As a result, even when a highly fineimage sensor dedicated for taking a still image is used in shooting amoving image, the image sensor can efficiently perform pixel process,therefore, an adequate frame rate can be set more easily also inshooting a moving image.

INDUSTRIAL APPLICABILITY

The idea of the above described embodiments can be applied not only tothe video camera 100 but also to a digital still camera, an informationterminal in which an imaging device is installed, and the like.

What is claimed is:
 1. An imaging apparatus comprising an imaging devicewhich includes a plurality of pixels and is operable to generate imageinformation for each pixel from received light, wherein each of theplurality of pixels includes one of first to fourth color filters, eachof the first to the fourth color filters has different spectralcharacteristics, the fourth color filter has the highest lighttransmittance among the color filters, the first to the fourth colorfilters are arranged in a specific array, the specific array for thefirst to third color filters except for the fourth filter is not a Bayerarray, the specific array has first to third centroids which make aBayer array, the first centroid is a centroid of a plurality of pixelswhich are used in a first pixel addition process performed on pixelinformation generated based on lights transmitted through the firstcolor filters, the second centroid is a centroid of a plurality ofpixels which are used in a second pixel addition process performed onthe pixel information generated based on lights transmitted through thesecond color filters, and the third centroid is a centroid of aplurality of pixels which are used in a third pixel addition processperformed on the pixel information generated based on lights transmittedthrough the third color filters, and pixel information regarding a colorcorresponding to the first color filters is generated by the first pixeladdition process, pixel information regarding a color corresponding tothe second color filters is generated by the second pixel additionprocess, and pixel information regarding a color corresponding to thethird color filters is generated by the third pixel addition process. 2.The imaging apparatus according to claim 1, wherein the fourth colorfilters are arrayed so that the centroid of the plurality of pixelswhich are used in a fourth pixel addition process performed on the pixelinformation generated based on lights transmitted through the fourthcolor filters is placed at the centroid of the first to the thirdcentroids, pixel information regarding a color corresponding to thefourth color filters is generated by the fourth pixel addition process.3. The imaging apparatus according to claim 2, wherein the fourth colorfilter is a W filter.
 4. The imaging apparatus according to claim 1,wherein the third color filters are arranged in checkered pattern. 5.The imaging apparatus according to claim 1, wherein weight set in eachof the first to third pixel addition processes is made more on a pixelcloser to the centroid of the pixels.
 6. The imaging apparatus accordingto claim 1, wherein the imaging device has a pixel adder which performsthe first to third pixel addition processes.
 7. The imaging apparatusaccording to claim 1, wherein the first color filter is an R filter, thesecond color filter is a B filter, and the third color filter is a Gfilter.
 8. The imaging apparatus according to claim 1, wherein theimaging apparatus further includes an adder operable to perform pixeladdition on an output signal from each pixel during a pixel additionmode, and to not perform the pixel addition during a pixel non-additionmode.
 9. The imaging apparatus according to claim 8, wherein the pixeladdition mode and pixel non-addition mode of the adder are selectable bya user.
 10. An imaging device which comprises a plurality of pixels andis operable to generate image information for each pixel from a receivedlight, wherein each of the plurality of pixels includes one of first tofourth color filters, each of the first to the fourth color filters havedifferent spectral characteristics, the fourth color filter has thehighest light transmittance among the color filters, the first to thefourth color filters are arranged in a specific array, the specificarray for the first to third color filters except for the fourth filteris not a Bayer array, the specific array has first to third centroidswhich make a Bayer array, the first centroid is a centroid of aplurality of pixels which are used in a first pixel addition processperformed on pixel information generated based on light transmittedthrough the first color filters, the second centroid is a centroid of aplurality of pixels which are used in a second pixel addition processperformed on the pixel information generated based on light transmittedthrough the second color filters, and the third centroid is a centroidof a plurality of pixels which are used in a third pixel additionprocess performed on the pixel information generated based on lighttransmitted through the third color filters, and pixel informationregarding a color corresponding to the first color filters is generatedby the first pixel addition process, pixel information regarding a colorcorresponding to the second color filters is generated by the secondpixel addition process, and pixel information regarding a colorcorresponding to the third color filters is generated by the third pixeladdition process.
 11. The imaging device according to claim 10, whereinthe fourth color filters are arrayed so that the centroid of theplurality of pixels which are used in a fourth pixel addition processperformed on the pixel information generated based on light transmittedthrough the fourth color filters is placed at the centroid of the firstto the third centroids, pixel information regarding a colorcorresponding to the fourth color filters is generated by the fourthpixel addition process.
 12. The imaging device according to claim 10,wherein the third color filters are arranged in checkered pattern. 13.The imaging device according to claim 10, wherein weight set in each ofthe first to third pixel addition processes is made more on a pixelcloser to the centroid of the pixels.
 14. The imaging device accordingto claim 10, wherein the imaging device has a pixel adder which performsthe first to third pixel addition processes.
 15. The imaging deviceaccording to claim 10, wherein the first color filter is an R filter,the second color filter is a B filter, and the third color filter is a Gfilter.
 16. The imaging device according to claim 10, wherein the fourthcolor filter is a W filter.
 17. The imaging device according to claim10, wherein the imaging device further includes an adder operable toperform pixel addition on an output signal from each pixel during apixel addition mode, and to not perform the pixel addition during apixel non-addition mode.
 18. The imaging device according to claim 17,wherein the pixel addition mode and pixel non-addition mode of the adderare selectable by a user.